Browsing by Author "Kurt H."
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Item Open Access Asymmetric light propagation in chirped photonic crystal waveguides(Optical Society of American (OSA), 2012) Kurt H.; Yilmaz, D.; Akosman, A.E.; Özbay, EkmelWe report numerical and experimental investigations of asymmetric light propagation in a newly designed photonic structure that is formed by creating a chirped photonic crystal (PC) waveguide. The use of a non-symmetric distribution of unit cells of PC ensures the obtaining of asymmetric light propagation. Properly designing the spatial modulation of a PC waveguide inherently modifies the band structure. That in turn induces asymmetry for the light's followed path. The investigation of the transmission characteristics of this structure reveals optical diode like transmission behavior. The amount of power collected at the output of the waveguide centerline is different for the forward and backward propagation directions in the designed configuration. The advantageous properties of the proposed approach are the linear optic concept, compact configuration and compatibility with the integrated photonics. These features are expected to hold great potential for implementing practical optical rectifier-type devices. © 2012 Optical Society of America.Item Open Access Compact wavelength de-multiplexer design using slow light regime of photonic crystal waveguides(Optical Society of American (OSA), 2011) Akosman, A.E.; Mutlu, M.; Kurt H.; Özbay, EkmelWe demonstrate the operation of a compact wavelength demultiplexer using cascaded single-mode photonic crystal waveguides utilizing the slow light regime. By altering the dielectric filling factors of each waveguide segment, we numerically and experimentally show that different frequencies are separated at different locations along the waveguide. In other words, the beams of different wavelengths are spatially dropped along the transverse to the propagation direction. We numerically verified the spatial shifts of certain wavelengths by using the two-dimensional finite-difference time-domain method. The presented design can be extended to de-multiplex more wavelengths by concatenating additional photonic crystal waveguides with different filling factors. © 2011 Optical Society of America.Item Open Access Large bandwidth mode order converter by differential waveguides(Optical Society of American (OSA), 2015) Oner, B.B.; Üstün, K.; Kurt H.; Okyay, Ali Kemal; Turhan-Sayan G.In this article, we propose a large bandwidth mode-order converter design by dielectric waveguides with equal lengths but different cross-sectional areas. The efficient conversion between even and odd modes is verified by inducing required phase difference between the equal length waveguides of different widths. Y-junctions are composed of both tapered mode splitter and combiner to connect mono-mode waveguide to multi-mode waveguide. The converted mode profiles at the output port show that the device operates successfully at designed wavelengths with wide bandwidth. This study provides a novel technique to implement compact mode order converters and direction selective/sensitive photonic structures. © 2015 Optical Society of America.Item Open Access Photonic crystal based multi-mode high-qcavity(IEEE, 2011) Akosman, Ahmet Emin; Mutlu, Mehmet; Kurt H.; Özbay, EkmelAn optical race-track has been investigated in order to obtain a multi resonant structure with high-Q factors. Photonic crystal based structure provides strong field confinement and scalability in the dimensions of the structure. The average value of the quality factors at the resonances have been calculated to be on the order of ∼105. © 2011 IEEE.